new proposal to vector intrinsics

[Sa Liu]

Tobias Burnus <burnus@net-b.de> wrote on 18.01.2008 19:12:44:

> Sa Liu wrote:
> > How about the changes in frontend concerning recognition of backend
> > builtins? Will this be acceptable in gfotran?
> It is not completely clear what you mean by this. 

What I mean is about checking and resolving backend builtins. When reading 
the generated mod file from vec_intrinsics module, the function name 
builtin_vec_add_int is saved in the program's namespace, and its binding 
label "__builtin_altivec_vadduwm" could be used to connect the backend 
builtin, i.e. to bind this symbol's backend_decl with its function decl.
> module vec_intrinsics
>   implicit none
>
>   interface
>     function builtin_vec_add_int(a, b) result(c) bind(c, 
> name="__builtin_altivec_vadduwm")
>           use, intrinsic :: iso_c_binding
>           integer (c_int), intent(in):: a(4), b(4)
>           integer(c_int) :: c(4)
>     end function builtin_vec_add_int

Fortunately we already have these decls in frontend. When the frontend 
initialize builtins, it also calls targetm.init_buitins() to initialize 
backend builtins. The idea here is to build a new gfc_namspace, say 
backend_intrinsic_namespace, then keep the decls in it, and later bind the 

decls with there corresponding symbols in the interface module. 

We thought about building the new namespace in gfc_builtin_function, and 
in gfc_get_extern_function_decl, search the decl in this namespace, link 
the symbol with it if found any, before the frontend builds a new one. 
Through the backend_decl the frontend can then resolve the intrinsic 
functions. This requires some changes in f95-lang.c and trans-decl.c.

> For the vector type
> itself, I assume one needs to support somewhere the conversion
> TYPE(vec_*) to attribute((vector)), even if the type itself is defined
> in a module.

We thought of adding a private component to the TYPE(vec_*) in order to 
distinguish vector type from user defined derived types with the same 
array components. Is the attribute((vector)) for the same purpose or 
anything else?


Thanks!
Sa